定义一个结构体变量(包括年月日)。计算该日在本年中是第几天
#include<iostream>
using namespace std;
struct date
{
    int year;
    int month;
    int day;
};
int main()
{
    date x;
    int days=0,i;
    int Days[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    cin>>x.year>>x.month >>x.day;
    for(i=1;i<x.month;i++)
    {
        days+=Days[i];
    }
    days=days+x.day; 
    if(x.month>2)
    {
        if((x.year%4==0&&x.year%100!=0)||x.year%400==0)
        {
            days=days+1;
        }
    }
    cout<<days;
    return 0;
}